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- May 16, 2016
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By going to a 3 phase motor, there are no start/stop issues to deal with. Using a VFD you get both controlled acceleration and deceleration to whatever degree you want. I have done a number of smaller lathe conversions, often go with a 2 Hp motor if it will fit. Alternatively you could go with a DC motor and controller with braking. A lot easier then adding clutches and brakes and the space it would take up. There are also brake motors for either single phase or 3 phase, but they are pricey. Expense wise, if you do both a mechanical brake and some form of clutch, a VFD and 3 phase motor would probably be similar in cost.
Slamming the lathe to a stop, I would be less concerned about the motor and more concerned of the longevity of the gear train/drive. There is a lot of momentum in the system, a mechanical brake slammed on at speed generates a lot of braking force and something would eventually break. VFDs you can control both the time an slope of the braking rate, so would be a bit gentler on the system. I normally use 3 second braking with VFDs, 1 second only for slow speeds or emergency braking.
I had thought of 3 phase and VFD etc., and even though I have 3 phase available I decided against it, I could yet go that way but just looking at alternatives.
The brake would rarely ever be used. it is strictly emergency use only. Just thinking out loud.[/QUOTE]
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